From: Tom Lane <tgl@sss.pgh.pa.us>
To: Romuald Brunet <romuald.brunet@gmail.com>
Cc: pgsql-performance@postgresql.org
Subject: Re: Slower query after psql changed it's execution plan
Date: Mon, 23 Mar 2009 10:26:38 -0400
Message-ID: <8646.1237818398@sss.pgh.pa.us> (raw)
In-Reply-To: <8ae589230903230652n294f456dn6e3ec7a39bb4c0aa@mail.gmail.com>
References: <8ae589230903230652n294f456dn6e3ec7a39bb4c0aa@mail.gmail.com>
Romuald Brunet <romuald.brunet@gmail.com> writes:
> After some investigation, we found out that the PostgreSQL server
> (8.1) changed the execution plan (I'm assuming because the number of
> rows increased).
The problem seems to be that the estimate for the number of rows fetched
from dc_post changed drastically --- it was in the right ballpark, and
now it's off by a factor of 30. Why is that? Maybe you had had a
special statistics target setting, and it got dropped?
> The statistics are at the default value everywhere (10)
Almost certainly not enough.
regards, tom lane
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Subject: Re: Slower query after psql changed it's execution plan
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